Intermittency Constraint

The moving parts are timing, demand, and substitution. Electricity demand continues when weather-dependent generation stops, so installed capacity does not guarantee usable supply at a particular hour. Storage can shift earlier production forward; backup generation can replace it. Either way, the supporting machinery belongs inside the system boundary—not outside the calculation. This turns intermittency into one face of the energy-trilemma: cleaner generation may require additional spending or operational complexity to remain available. It is also a constraint rather than a guarantee: abundant generating potential makes supply possible, but does not ensure delivery when demanded.

Intermittency does not mean solar or wind is useless, nor that the constraint is permanent. Storage directly addresses the timing mismatch. The narrower claim is that generation and dependable, round-the-clock supply are different products. Treating that mismatch as an operating constraint clarifies what must be engineered around; it does not prove that any particular storage or backup design is uneconomic.